1. Field of the Invention
The present invention relates to a lens for use with markers for vehicles that have a light-emitting diode (LED) light source and, more particularly, to a lens having a projection for increasing visibility from the side of the vehicle to which the marker is affixed.
2. Description of Related Art
Vehicle markers, such as clearance markers, reflective devices and similar types of markers used on vehicles are typically mounted to the front, rear and sides of a vehicle, such as an automobile or truck/trailer combination, to indicate the overall height, width and length of the vehicle. For example, § 108 of the Federal Motor Vehicle Safety Standards and Regulations (“FMVSS”) requires all vehicles to have a certain number of vehicle markers, including clearance markers and reflective devices, mounted permanently to a part of the vehicle. According to the FMVSS, the Society of Automotive Engineers (“SAE”) is the organizational body directed to setting standards and recommended practices for compliance with the provisions of the FMVSS. The purpose of these standards and practices is to reduce traffic collisions and deaths and injuries resulting therefrom, by providing adequate illumination of both the roadway and the vehicle in daylight and in darkness (or other conditions of reduced visibility).
Vehicle markers are mounted on the vehicle to provide light to the front, rear and sides of a vehicle in order to indicate the overall width, height and length of the vehicle. For example, according to SAE standards, a red clearance marker is used to indicate the rear of the vehicle and an amber clearance marker is used to indicate the front of the vehicle. Furthermore, a “PC” rating is an indication that according to the SAE standards, the marker can be seen easily from both the side and the front. Therefore, to achieve a “PC” rating, the clearance marker must emit light in an arc-like pattern.
Vehicle markers include a housing, which includes the light source, and a lens, which protects the light source from the natural elements. Typically, the light source for such markers is either a standard high-intensity incandescent bulb, which has a relatively short life span and is susceptible to damage, or a light-emitting diode (LED), which has a greater operating life.
One of the problems associated with using an LED light source is the difficulty in spreading the illumination in a longitudinal direction, i.e., an arc-like pattern. While LEDs can have an operating life of up to 100,000 hours before degradation commences, the light emitted from LEDs is in a narrow cone-shaped pattern. More specifically, an LED is a directional light source in which the maximum emitted light is in a direction perpendicular to the light surface. A typical radiation pattern for an LED is within 20° of the direction of the maximum light, which is significantly less than the SAE standard for visibility for a side clearance marker. Accordingly, an LED light source is not ordinarily used for side clearance markers because of the inability of the LED clearance markers presently known in the art to spread the light in an arc-like pattern as required by SAE standards.
Thus, there exists a need to provide a lens suitable for use with an LED vehicle marker which is relatively inexpensive and easy to manufacture and which provides the requisite illumination pattern.